DizzyEdge

I noticed today that my coolent temperature gauge is only getting as high as a few mms above the C line, or a hair above the C itself, even after 30+ minutes of driving. Climate control blows hot as normal.

Is there any easy way to determine if it's bad temp readings from the sensor, or a stuck open thermostat?

Also perhaps related, perhaps not, shifting got really bad today, like 3500-5000rpm before shifting, which from googling in general seemed to indicate at least with some cars that could have to do with bad temp readings. Any thoughts if it could be related to the always cold temp readings?

Thanks!

PS: 1996 Maxima GLE auto

komik

Check the connection to the engine coolant temp sensor. It is located where the upper radiator hose meets the block, pictured below.
If it seems secure, page 82 of section EL of the FSM details the procedure for testing the gauge in the dash. Page 183 of section EC of the FSM details the procedure for testing the sensor.

User BenL has been kind enough to upload the full 4th Gen FSM here

From this thread: https://maxima.org/forums/4th-genera...placement.html

DizzyEdge

Thanks for that Komik. I don't think I'll be able to test the temp dial on the instrument cluster as the temps outside are going down far below freezing for the foreseeable future and I'm sure the instrument cluster cowling will shatter when I have to bend it to remove the cluster. One thing too, if the temp guage and the temp signal to the computer are from different sensors, and both are giving indications of cold temps, would that mean that it's unlikely that they're both giving wrong signals, ie the temp actually is cold due to a bad thermostat?

Also, I started the car with the rad cap off, and for the first.. 20 seconds? the coolent stood still, but after 20 seconds it slowly started rising and running over the top. the temp of that coolant at start would have been about -6C/20F.

I have to do all my work outside in sub zero temps so I'm trying to do as much symptom analysis as possible from the warmth of my home haha.

Thanks

Rit

iTrader: (3)

I have found that it is fairly easy to lower the steering column by using a deep socket on two nuts that hold up the column from below - by where your legs go. It takes a bit of time - maybe 5 minutes - but it makes it tons easier to get the cluster out without having to bend the cowling.

CS_AR

There are two coolant temperature sensors on the coolant pipe that connects to the upper radiator hose.

In the picture below, the smaller blue one (single wire) is the Coolant Temp Sender that drives the coolant temperature reading on the instrument panel.

The larger white one (double wire) is the Engine Coolant Temperature sensor that communicates with the Engine Control Unit (ECU) for engine operation.

I like to use the BWD Intermotor brand for those sensors. The Coolant Temp Sender SMP TS391 Intermotor product is $8.01 at RockAuto.com.

I just replaced both sensors on my 98 model as part of a midlife refresh. Three years ago I replaced both on the 99 model with SMP parts that you see in the picture below.

Since those sensors are low cost, and they can cause headaches when they malfunction, I just replace them as part of the midlife refresh process.

Rit

iTrader: (3)

Wow - your engine looks like it just came off of the factory assembly line. Impressive.

DizzyEdge

Yeah due to the low cost I think I'm just going to replace both sensors and the thermostat

CS_AR

We like OEM thermostats and gaskets on here. You can usually get an OEM thermostat from a dealer for under $40. Be careful not to over torque the thermostat bolts. I have broken one of those bolts in the past by applying too much torque. I use a 1/4 drive when working with thermostat bolts for that reason. Thankfully I had a spare and could remove it without having to use a drill to remove it.

DizzyEdge

So 6 months later I'm actually getting around to this (obviously this isn't my DD).

Since they were so cheap I replaced the thermostat and both sensors.

No change after the thermostat replacement, but there is definitely a change after replacing the sensors:

- the temp gauge now works
- the car now stalls after 5 seconds with a Engine coolant temperature sensor code. Ironically there was no ECTS code before I replaced the sensor...
It actually didn't stall the first couple of times although it idled very low, like 400-500 rpm in P or N (but over 1000rpm when in D or R)

I haven't been able to test if the transmissions shifts properly yet (the transmission problems started the exact same drive as the temp guage problems)

Thoughts?

JvG

I would make sure that the connector wire to the engine temperature sensor is bright and shiny. Some corrosion there would act a lot like a defective ets.

If the problem still occurs once that connector terminal has been cleaned, reinstall the old ects, then see what happens.

I think that a corroded terminal is the issue.

DizzyEdge

Ok false alarm I guess, for some reason I thought the car would run with some of the front plastic cowling/tubing off (just the parts that lead into the filter box.
Put it back on and it is much better, idles at 500 though straight from start, but sticks there. Drove it around for 20 mins, still shifts a bit high (2500 rpm from 2nd to 3rd), and not super smoothly, but it's an improvement. Not sure if the temp sensor code is still in the computer. I may drive it to work tomorrow and then pull codes when I get home, assuming I make it home.

DizzyEdge

This car has sat for a long time on dirt/grass, I do worry about unending corrosion issues with the electrical. That said the female wiring harness plug that plugs into the ets looks spotless, and of course the male tabs on the sensor itself are brand new. I did try the old ets but no change.

But like I said it appears to be somewhat running ok now, so I'll take it for some spins to work this week and see how it goes.